Getting 84% Apparent Attenuation with US-05? Why so high?

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Jayhem

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So since I have switched to AG my Apparent (Measured) Attenuation has gone up significantly. When I did partial mash I was getting 75%. Now that I'm AG I'm getting 83-85%.

For example my last batch (brown ale):

OG @ 65F = 1.051
FG @ 65F = 1.008

According to this calculator: http://pint.com.au/calculators/alcohol/
My Apparent attenuation is 84% whereas US-05 yeast is only supposed to attenuate to 75%.

Any idea what might be causing this? My beers taste fine but I'm really not wanting 5-6% abv in beers that only have a 1.050 OG! Do I need to switch yeasts? Mash at a higher temp?
 
Your thermometer may be off and you may be mashing a lot lower than you think you are.
 
At what temperature are you fermenting? A higher mash temp should reduce attenuation.
I have a Johnson temp control running my fermentation chamber which I set at 60F for the first 7 days and then 65F for the rest of the 21 day primary. My beer temp never gets above 66F according to my temp strips which I wrap a towel around to be sure they are measuring FV temp and not air temp.

Your thermometer may be off and you may be mashing a lot lower than you think you are.

I was wondering if this could be my problem. I mash at a measured 150-154F but my thermometer is just a lab thermometer like this:
lab+thermometer.png



What is the best way to calibrate it?
 
How long are you mashing for?

It is some combination of too low mash temp and too long of a mash. And grain bill, of course. It is not the fermentation temp.


You can calibrate using the standard ice bath for the low end, and boiling water for the high end. That is no guarantee that the thermometer is accurate in the mash temp range, but at least then you'll know if it is systematically off in one direction or another.


Personally I feel that the attenuation numbers given by yeast vendors are more guidelines. As in, US-05 will tend to attenuate more than S-04 (mostly due to flocculation, IMO). However the mash and grain bill play such a huge role in attenuation that there is no way you can just use those numbers reliably and expect your beers to attenuate 75% or whatever. By tweaking my recipe designs I have gotten over 90% attenuation from US-05 for one recipe, and less than 70% for another.
 
How long are you mashing for?

It is some combination of too low mash temp and too long of a mash. It is not the fermentation temp.


You can calibrate using the standard ice bath for the low end, and boiling water for the high end. That is no guarantee that the thermometer is accurate in the mash temp range, but at least then you'll know if it is systematically off in one direction or another.


I mash for 60 minutes and batch sparge with 168F water. My mash temp tends to stay pretty stable, maybe dropping 2 degrees F in 60 minutes.

I can give that a try. What types of thermometers are the most accurate? Seems like a lot of homebrewers are using digital probes for their mash tuns.
 
How long is your sparge?


I use a thermapen but it is rather pricey. However, it totally rocks as a thermometer. I know plenty of folks use some of the cheaper digital instant-read thermometers and like them.
 
How long is your sparge?


I use a thermapen but it is rather pricey. However, it totally rocks as a thermometer. I know plenty of folks use some of the cheaper digital instant-read thermometers and like them.

I sparge in 3 parts, usually about 1.5 gal per volume or as needed to reach my pre-boil volume in the brew pot. I pour the sparge water in, give it a stir, let it sit 3-5 min and then lauter my 2nd+ runnings that way. Is this an OK method?
 
No I mean how long is your sparge, in minutes?

One thing that might be going on is that typically your sparge water might be 168, but your grain bed temp is lower, so you are still getting alpha and beta amylase the whole time you are sparging. If you have a longer mash/sparge in the range where beta amylase is still taking place, you are going to get a more fermentable wort.


EDIT:

However, this whole line of reasoning is a bit of a stretch. My money is on the mash temps being lower than you think. I would just increase your target mash temp a couple of degrees on your next brew and see how that ferments out.
 
No I mean how long is your sparge, in minutes?

One thing that might be going on is that typically your sparge water might be 168, but your grain bed temp is lower, so you are still getting alpha and beta amylase the whole time you are sparging. If you have a longer mash/sparge in the range where beta amylase is still taking place, you are going to get a more fermentable wort.


EDIT:

However, this whole line of reasoning is a bit of a stretch. My money is on the mash temps being lower than you think. I would just increase your target mash temp a couple of degrees on your next brew and see how that ferments out.

I think you are asking how long I leave the sparge water in the grain bed but you could also mean how long does it take to lauter the sparge through as wort runnings. I actually pour in water that is about 174F so that my grain bed/water temp rises to 167/168F for 3-5 minutes, then lauter for about 3-5 minutes more.

I actually mashed my last brew (currently in primary) at a higher temp to see if it makes a difference. I mashed at an "indicated" 156F with the same thermometer. We shall see! thanks for the advice so far.

- J
 
If I mash at 152 with Vienna and wheat only and no crystal/dextrin or any roasted malts I get about the same attenuation. S05 is a beast. Try a higher mash at 156 or some crystal malt. Or you can try a less attenuative yeast like 04 or Another American yeast like Dennys or American Ale 2.
 
Yup, US-05 took my last IPA down to 1.004, whoops! But like others are saying, mashing a little higher should fix that to some degree, I mashed at about 150 F.
 
I was wondering if this could be my problem. I mash at a measured 150-154F but my thermometer is just a lab thermometer like this:
lab+thermometer.png



What is the best way to calibrate it?

There is no way to adjust this thermometer, which by the way is probably more accurate (but less convenient) than what most of us use. You can test it in ice water and boiling water to see how close it is. If it is not dead on, then you'll have to add or subtract by the amount it is off. Simple enough.

Since you are doing all grain, how you mash can have a large affect on the apparent attenuation.
 
Yup, US-05 took my last IPA down to 1.004, whoops! But like others are saying, mashing a little higher should fix that to some degree, I mashed at about 150 F.

it took my last PA to 1.005 (or 1.007...not sure my hydrometer is reading correctly). I mashed at 152 and dropped a degree or 2 during the mash. i'm not too concerned...the sample tasted good!
 
I just tried the brown ale that finished @ 1.008 and it doesn't taste dry since it does have 10oz of pale chocolate malt + 1lb of C-60 malt.

Any other dry yeasts that won't attenuate so much? I also have Nottingham.
 
How long is your sparge?


I use a thermapen but it is rather pricey. However, it totally rocks as a thermometer. I know plenty of folks use some of the cheaper digital instant-read thermometers and like them.

I used to use one of those glass thermometers with the red alcohol inside from my LHBS because they were supposed to be accurate, but I found that it wasn't very accurate at all, so now have switched to a cheap digital probe thermometer and it is surprisingly accurate. Hit 32.3 in an ice slurry and seemed to be accurate at the boiling end as well. I bought it from focalprice for like 6 bucks shipped. Only down side is it is kind of slow.
 
Any other dry yeasts that won't attenuate so much? I also have Nottingham.

Depending on your system you could use S-04. I would use it if I wanted a less dry american ale, but only with a big pitch, plenty of oxygen, and cold, slowly rising fermentation temps. Even then I'd still worry about diacetyl.

I think this problem is better solved in the mash, especially if you've got doubts about your measurements.
 
Personally I don't think S-04 is a good substitute for US-05. S-04 tends to have a lot more fruitiness. I think of it as more of an English-style ale yeast.
 
So Mash temps are the most important thing here? Mash @ 154F for 50-60 minutes for less attenuation/sweeter beer?
 
Grain bill also plays a big part. If you have 30% crystal malts in your grain bill, you are not going to get much attenuation.

Assuming the same grain bill and healthy pitching rates, a higher mash temp will have the biggest impact on attenuation IMO.

Some higher-flocculating yeast strains (like S-04) don't attenuate as well normally because they drop out pretty quickly and form a tight clump on the bottom of the fermenter. If you manually agitate the yeast cake a bit, though, you can get somewhat higher attenuation out of them.
 
After I switched to AG I was having a problem with too low FG. I started doing a mash out and have had no problem since. Seems like conversion was continuing while first and second runnings were sitting in the BK before actually starting boiling. I was also doing double batch sparge.
 
I'm confused. I thought that a higher temp in the mash and sparge means more sugars from the grain. But this thread seems to indicate that the lower the temp, the more 'fermentable' sugar? What am I missing?
 
I'm confused. I thought that a higher temp in the mash and sparge means more sugars from the grain. But this thread seems to indicate that the lower the temp, the more 'fermentable' sugar? What am I missing?

you have it backwards... lower mash temp will produce more fermentable wort than a higher temp mash.
 
you have it backwards... lower mash temp will produce more fermentable wort than a higher temp mash.

Cool, thanks for the answer.. but why do I read that sparging with hotter water is to rinse sugars from the grain?
 
After I switched to AG I was having a problem with too low FG. I started doing a mash out and have had no problem since. Seems like conversion was continuing while first and second runnings were sitting in the BK before actually starting boiling. I was also doing double batch sparge.

So what is the solution? Should I start my boil with the first runnings while I'm sparging into a second container and then add the second runnings to the brew kettle once I'm done sparging?
 
Cool, thanks for the answer.. but why do I read that sparging with hotter water is to rinse sugars from the grain?

typically during the sparge you are just "rinsing", the conversion is done during the mash (with lower temps).
 
Cool, thanks for the answer.. but why do I read that sparging with hotter water is to rinse sugars from the grain?

This is correct. Whether the water needs to be hot or not is debated. Probably the biggest advantage of a hot sparge is that hot liquids simply flow faster. The sugars are already dissolved so, as far as that aspect is concerned , tempeature make no difference. The sparge is simply moving the sugars away from the spent grain. Cold water will also "wash" the sugars off the spent grain.
 
So what is the solution? Should I start my boil with the first runnings while I'm sparging into a second container and then add the second runnings to the brew kettle once I'm done sparging?

I do a mash out first (I tend to fly sparge), and I do start the first runnings on the heat as the sparge finishes. This holds the fermentability profile of the wort, if that makes sense.

But you don't have to use a second container, unless you are gravity draining and the kettle is too high- you just drain your runnings into the brewpot.
 
This is correct. Whether the water needs to be hot or not is debated. Probably the biggest advantage of a hot sparge is that hot liquids simply flow faster. The sugars are already dissolved so, as far as that aspect is concerned , tempeature make no difference. The sparge is simply moving the sugars away from the spent grain. Cold water will also "wash" the sugars off the spent grain.

Thanks. This is starting to make a lot more sense now.
 
I do a mash out first (I tend to fly sparge), and I do start the first runnings on the heat as the sparge finishes. This holds the fermentability profile of the wort, if that makes sense.

But you don't have to use a second container, unless you are gravity draining and the kettle is too high- you just drain your runnings into the brewpot.

Thanks, remind me again how you mash out? I can easily place my mash tun on top of my BBQ grill which is right next to my brew pot on the deck on brew day to collect the second runnings while the wort is on the flame! :mug:
 
Thanks, remind me again how you mash out? I can easily place my mash tun on top of my BBQ grill which is right next to my brew pot on the deck on brew day to collect the second runnings while the wort is on the flame! :mug:

I add some boiling water (calculated by Beersmith for me, as far as the amount), to bring the grainbed up to 168 and stir well. Then I start my sparge, drizzling the water in the top at the same speed as I drain.
 
I add some boiling water (calculated by Beersmith for me, as far as the amount), to bring the grainbed up to 168 and stir well. Then I start my sparge, drizzling the water in the top at the same speed as I drain.

Ah. Then I suppose I have been mashing out without realizing it. I batch sparge but I pour in water that is about 170F and stir well, bring the grainbed up to about 165F and then lauter slowly, than add 165F water in one more batch to finish the sparge and get my pre-boil volume up to the right level. Been getting 75% efficiency this way.
 
Ah. Then I suppose I have been mashing out without realizing it. I batch sparge but I pour in water that is about 170F and stir well, bring the grainbed up to about 165F and then lauter slowly, than add 165F water in one more batch to finish the sparge and get my pre-boil volume up to the right level. Been getting 75% efficiency this way.

Yes, that takes the place of a traditional "mash out", when you batch sparge with hotter water. No need to lauter slowly when you batch sparge, though. The beauty of batch sparging is that you add the first round of sparge water, stir extremely well, vorlauf and let 'er rip! It takes like 10 minutes for me to batch sparge, so sometimes I still batch sparge when pressed for time.
 
Yes, that takes the place of a traditional "mash out", when you batch sparge with hotter water. No need to lauter slowly when you batch sparge, though. The beauty of batch sparging is that you add the first round of sparge water, stir extremely well, vorlauf and let 'er rip! It takes like 10 minutes for me to batch sparge, so sometimes I still batch sparge when pressed for time.

Am I hurting anything by lautering slowly? Seems less grain bits make it into the brew pot if I keep it slow. I'm not talking 1 gallon per 30 min slow, maybe 1 gallon in 5-7 min.
 
Am I hurting anything by lautering slowly? Seems less grain bits make it into the brew pot if I keep it slow. I'm not talking 1 gallon per 30 min slow, maybe 1 gallon in 5-7 min.

Well, no....................but you're the one with overattenuation issues, right?

Just' sayin'!

I have a strong feeling that the slow lautering and low "mash out" temps of 170 means that could be part of the overattenuation that you're experiencing.
 
Well, no....................but you're the one with overattenuation issues, right?

Just' sayin'!

I have a strong feeling that the slow lautering and low "mash out" temps of 170 means that could be part of the overattenuation that you're experiencing.

Good advice! I will make some process changes on the next batch! :mug:
 
Well, no....................but you're the one with overattenuation issues, right?

Just' sayin'!

I have a strong feeling that the slow lautering and low "mash out" temps of 170 means that could be part of the overattenuation that you're experiencing.

I agree but if he says the grain bed temp is 165, though ought to be doing the trick. Unless his temperature measurements are actually wrong, in which case his mash temperature measurements are also wrong. So, bumping up the target mash temp should be the main focus IMO.
 
I agree but if he says the grain bed temp is 165, though ought to be doing the trick. Unless his temperature measurements are actually wrong, in which case his mash temperature measurements are also wrong. So, bumping up the target mash temp should be the main focus IMO.

I have a feeling that sparging with 170F water won't raise a bedtemp of 154 up to 165. But that's just based on personal experience.

I wonder if the OP has put his thermometer into an icebath yet? I'd guess the same as yooper. Low mash temps + long sparges (of less then mashout temps by my suspicion)= more fermentable wort.
 
I have a feeling that sparging with 170F water won't raise a bedtemp of 154 up to 165. But that's just based on personal experience.

I wonder if the OP has put his thermometer into an icebath yet? I'd guess the same as yooper. Low mash temps + long sparges (of less then mashout temps by my suspicion)= more fermentable wort.

OP here. I'm going run the thermometer ice-bath test this weekend and see how far off it is. will update.
 
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